Bioseparation Lab, Chemical-Physics Department, Faculty of Biochemical and Pharmaceutical Sciences, CONICET, FonCyT and CIUNR, National University of Rosario, Suipacha 570, S2002RLK Rosario, Argentina.
J Chromatogr B Analyt Technol Biomed Life Sci. 2010 Jun 1;878(19):1543-8. doi: 10.1016/j.jchromb.2010.04.008. Epub 2010 Apr 24.
Interactions between a model protein (bovine serum albumin--BSA) and the cationic polyelectrolyte, chitosan (Chi), have been characterized by turbidimetry, circular dichroism and fluorescence spectroscopy. It has been found that the conformation of the BSA does not change significantly during the chain interaction between BSA and chitosan forming the non-covalently linked complex. The effects of pH, ionic strength and anions which modify the water structure around BSA were evaluated in the chitosan-BSA complex formation. A net coulombic interaction force between BSA and Chi was found as the insoluble complex formation decreased after the addition of NaCl. Around 80% of the BSA in solution precipitates with the Chi addition. A concentration of 0.05% (w/v) Chi was necessary to precipitate the protein, with a stoichiometry of 6.9 g BSA/g Chi. No modification of the tertiary and secondary structure of BSA was observed when the precipitate was dissolved by changing the pH of the medium. Chitosan proved to be a useful framework to isolate proteins with a slightly acid isoelectrical pH by means of precipitation.
用浊度法、圆二色性和荧光光谱法研究了模型蛋白（牛血清白蛋白-BSA）与阳离子聚合物壳聚糖（Chi）之间的相互作用。结果发现，在 BSA 与壳聚糖形成非共价连接复合物的链相互作用过程中，BSA 的构象没有明显变化。评估了 pH 值、离子强度和改变 BSA 周围水分子结构的阴离子对壳聚糖-BSA 复合物形成的影响。发现 BSA 和 Chi 之间存在净库仑相互作用力，因为添加 NaCl 后不溶性复合物的形成减少。添加 Chi 后，约 80%的 BSA 在溶液中沉淀。添加 0.05%（w/v）的 Chi 即可沉淀蛋白质，BSA/Chi 的计量比为 6.9 g BSA/g Chi。当通过改变介质的 pH 值溶解沉淀时，BSA 的三级和二级结构没有发生变化。壳聚糖被证明是一种有用的框架，可以通过沉淀将等电点略低于酸性的蛋白质分离出来。
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